The radif of Esma'il Khan Mehrtash, which is a result of the lessons he took from the masters of Iranian music and also most probably a result of his creativity within the framework of these lessons, is a radif with characteristics often different from other vocal radifs. For example, Shushtari-Mansuri in this radif is an independent avaz. So the number of avazes in this radif is six.
Mohammad Montasheri, a very close and talented student of the late Mehrtash, has performed the greatest part of the present radif by referring to his personal memory. Some parts of this radif have been recorded on reels during the courses. Montasheri has had access to some of them and has been able to evaluate his work and diminish the probable deficiencies by referring to them. He was the closest student to Mehrtash and had a close relationship with him for 20 years. In the last years of the master's life, Montasheri could perform some parts of his master's radif or some of his compositions which he himself had forgotten. Besides, because he was trained only by Mehrtash, he has acquired a style that makes him the most competent interpreter of the radif of Mehrtash. He, as he himself says, knows the "spirit" of Mehrtash's works.